China
Africa
Explore chapters and articles related to this topic
Introduction to Cells, DNA, and Viruses
Published in Patricia G. Melloy, Viruses and Society, 2023
Before learning about viruses, it is useful to understand what they infect: our cells. It has been known for quite some time that our bodies are made of cells. Going back to the early 1800s, Matthias Schleiden and Theodor Schwann determined that all animals and plants are made of cells. Cells are defined philosophically as being the fundamental units of life and are distinctive for being able to reproduce themselves to make other cells. All these ideas (animals and plants are made of cells, cells are the fundamental units of life, cells give rise to other cells) put together became what is now called the cell theory (Alberts et al. 2019). From the point of view of chemical content, one can also define cells as containing many macromolecules needed for the processes of life, protected by the cell membrane. Although our cells are mostly made of water, the key macromolecules present are critical for cellular function, including nucleic acids, carbohydrates, proteins, and lipids. DNA and ribonucleic acids (RNA) are nucleic acids, made of building blocks called nucleotides. Proteins are made of amino acids. Carbohydrates are made of sugar subunits. Lipids, also known as fats, are made of fatty acids and glycerol. See Table 1.1 for key definitions.
Basic genetics and patterns of inheritance
Published in Hung N. Winn, Frank A. Chervenak, Roberto Romero, Clinical Maternal-Fetal Medicine Online, 2021
Errors in the sequence of nucleic acids of the DNA produce mutations in genes and often lead to genetic diseases. There are a variety of different kinds of mutations that can occur in genes. Some result in genetic disorders, while others may have no detrimental effect. The most common type of mutations include missense (single amino acid change), nonsense (insertion of stop codon with premature termination of translation), frameshift (insertion or deletion of nucleotides that alters downstream codons), splice site (incorrect splicing of introns), and promoter mutations (decreased transcription of mRNA). An expansion mutation occurs when there is insertion of many extra copies of a trinucleotide repeat; examples of disorders with this type of mutation are fragile X syndrome, Huntington disease, and myotonic dystrophy.
Clinical Basis of COVID-19
Published in Wenguang Xia, Xiaolin Huang, Rehabilitation from COVID-19, 2021
The advantage of nucleic acid testing is that it shortens the window period of infection detection and can detect infected persons early. The false negative of nucleic acid testing may be due to poor quality specimens. The possible influencing factors include improper collection, preservation, transportation, and handling of specimens, virus mutation, PCR inhibition, and so on. In addition, as 2019-nCoV is a single-stranded positive-stranded RNA virus with a large molecular weight, it is easy to mutate. Nucleic acid sequence mutations may occur in the process of transmission. If it is located in the primer binding area for nucleic acid amplification, false negative results will occur. It is suggested that multiple nucleic acid regions should be amplified to effectively avoid the influence of nucleic acid variation on the detection results. When the nucleic acid testing result is negative, only the negative result of this testing can be reported. The 2019-nCoV infection cannot be ruled out, and repeated confirmation is required.
Recent advances in anti-multidrug resistance for nano-drug delivery system
Published in Drug Delivery, 2022
Changduo Wang, Fashun Li, Tianao Zhang, Min Yu, Yong Sun
Nucleic acids are anionic biomacromolecules; thus, cationic lipid and polymer systems can electrostatically bind to RNA and facilitate the gene transfection. In previous reports, a number of functional vehicles have been widely used to achieve the nucleic acid and anticancer drugs simultaneous delivery. Cationic polymers can be designed as hydrophilic segments and covalently linked to hydrophobic groups, which do not only achieve chemotherapeutic drugs and siRNA codelivery but also further modify amphiphilic copolymer to possess more functions (Pan et al., 2019; Shen et al., 2014). Molecular beacons, which are widely used for molecular targets detection and imaging in living cells, were loaded in graphene oxide carriers with DOX and hybridized with the target mRNAs for silencing MDR1 mRNA and upstream ETS1 mRNA, which shows effective a P-gp expression inhibition and further reverse MDR (Li et al., 2018).
Effect of Wuzi Yanzong prescription on oligoasthenozoospermia rats based on UPLC-Q-TOF-MS metabolomics
Published in Pharmaceutical Biology, 2022
Zhimin Chen, Baohua Dong, Yunxiu Jiang, Ying Peng, Wenbing Li, Lingying Yu, Yongxiang Gao, Changjiang Hu
According to the enriched metabolic pathway, the most significant metabolic feature of oligoasthenozoospermia is the change of amino acid metabolism. A variety of amino acid metabolic pathways, including phenylalanine, tyrosine and tryptophan biosynthesis, phenylalanine metabolism, tyrosine metabolism, alanine, aspartate and glutamate metabolism, arginine and proline metabolism, suggest that amino acids play an important role in spermatogenesis, development and maturation. Free amino acids participate in the cellular metabolism of motile sperm and are the source of energy supplement, which can promote its activity and reduce the harmful effects of toxins. Essential amino acids are important raw materials for the synthesis of nucleic acids. Supplementing essential amino acids will improve the body's ability to synthesize nucleic acids and promote spermatogenesis (Han et al. 2017).
Poly(beta-amino ester)s as gene delivery vehicles: challenges and opportunities
Published in Expert Opinion on Drug Delivery, 2020
Johan Karlsson, Kelly R. Rhodes, Jordan J. Green, Stephany Y. Tzeng
Nucleic acid-based therapeutics have tremendous potential to be used for a wide range of unmet therapeutic needs and for personalized medicine. However, carriers are needed to enable nucleic acid delivery across biological barriers into cells, involving encapsulation, colloidal stability, cellular uptake, endosomal escape, intracellular release, and safety. We have in this review highlighted the use of PBAEs to facilitate efficient intracellular delivery, including current understanding of the structure-function relationships that are important for the design of PBAEs. A major advantage over many other delivery materials is that PBAEs are hydrolytically biodegradable in physiological conditions, and they can be synthesized to ensure that degradation byproducts are nontoxic. As described above, preclinical studies have demonstrated that PBAEs can be used for safe delivery.